The present invention relates to a resin-coated metal sheet with high reflectivity and excellent adhesion strength. Even when the resin-coated metal sheet is formed under severe conditions, such as by stretch-forming of the resin-coated metal sheet or by deep-drawing of the resin-coated metal sheet, delamination does not occur.
Recently, higher grades of decorative design are desired, together with higher grades of articles such as domestic electrical machinery and apparatus, audio devices, kitchen appliances, and interior finish materials. Higher grade decorative design is expressed by the decorativeness of the surface of the packing materials or other cases of these articles, in particular, in higher reflectivity of the surface. Further, decorative design can be expressed by the shape of the package which is formed by stretch-coating a resin-coated metal sheet or by deep drawing a resin-coated metal sheet. Accordingly, the requirement for a decorative steel sheet with higher vivid reflectivity and having a workable adhesion strength suitable for stretch-forming of the resin-coated metal sheet or by deep-drawing thereof is increasing.
In order to satisfy this requirement, various researches were conducted. For instance, one proposal involves a method of laminating a colored metal sheet with a transparent thermosetting resin film or thermoplastic resin film of 5 to 100 microns and a thermoplastic resin film of 5 to 50 microns thickness having H to 7B hardness, as disclosed in Japanese Patent Publication (Kokai) 55126 of 1991, Heisei 2. However, while this method provides vivid reflectivity, delamination occurs at the interface between two resin components or at the interface between the laminated resin layer and the colored metal sheet. Thus, the workable shape of the decorative metal sheet is limited.
Namely, in the prior art, it was extremely difficult to obtain a laminated metal sheet that has workability fit for stretch-forming of the resin-coated metal sheet or by deep-drawing thereof, which also has vivid reflectivity.
It is an object of the present invention to provide a resin-coated metal sheet which has a workable adhesion strength fit for stretch-forming of the resin-coated metal sheet of deep-drawing, as well as vivid reflectivity.
A resin-coated metal sheet of the present invention comprises a metal sheet as a base sheet, of which at least one surface is overlaid in sequential order from the metal sheet, a paint layer, a modified polyolefin resin layer of 5 to 100 microns thickness.
Further, a resin-coated metal sheet of the present invention of which at least one surface is overlaid in sequential order, a paint layer, a pattern and/or solid printing layer, a modified polyolefin resin layer of 5 to 100 microns thickness, an adhesive layer, and a transparent polyester resin film of 5 to 100 microns thickness.
Furthermore, a resin-coated metal sheet of the present invention comprises a metal sheet as a base sheet, of which at least one surface is overlaid in sequential order, a paint layer, a modified polyolefin resin layer of 5 to 10 microns thickness, an adhesive layer, and a transparent polyester resin film of 5 to 100 microns thickness.
In these resin-coated metal sheets of the present invention, the paint layer is preferably formed as a top coat layer of the transparent polyester resin film.
Furthermore, in the resin-coated metal sheets of the present invention, the adhesive layer and/or the printing layer desirably include aluminum pigment to mica pigment.
Since the modified polyolefin resin layer which is provided in between the transparent polyester resin film and the metal sheet has excellent adhesiveness to the printing layer, the paint layer and the polyester resin film, even if the resin-coated metal sheet is formed under severe conditions against the resin-coated metal sheet, such as deep drawing, delamination does not occur. Thus, excellent workable adhesion strength is shown. Further, the roughness of the surface of the metal sheet, and unevenness of several component (resin) layers are smoothed out by the modified polyolefin resin layer so that a resin-coated metal sheet having excellent vivid reflectivity can be produced.
Additionally, since the paint layer is formed as the top coated layer (what is called the xe2x80x9ctop coatxe2x80x9d) of the transparent polyester resin film, the scratch resistance of the resin-coated metal sheet which is required when the resin-coated metal sheet is formed or handled is improved.